Many reaction processes employ heat exchangers in order to transfer heat from one media to another without the media being in direct contact. The heat exchanger may be employed subsequent to the main reaction and in such cases are called post-reactor heat exchangers. Unfortunately, in some situations these post-reactor heat exchangers may become fouled due to impurities, for example, insoluble compounds building up in, for example, coils or tubes of the heat exchanger. The fouling reduces the cross sectional area for heat to be transferred and causes an increase in the resistance to heat transfer across the heat exchanger. This is because the thermal conductivity of the fouling layer is often low. Thus, fouling reduces the overall heat transfer coefficient and efficiency of the heat exchanger. A corresponding increase in pumping and maintenance cost may also result.
Accordingly, what is needed are improved processes which may assist in reducing or eliminating the fouling of equipment such as post-reactor heat exchangers.
Advantageously, improved reaction processes comprise reacting a mixture in a via a reaction in at least one reactor to form at least one product comprising a metal alkyl compound, metal oxide, or mixture thereof and then passing said product to a post-reactor heat exchanger. The improvement comprises one or more of the following:
(1) reacting said metal alkyl compound with an acid to produce a soluble metal ester; or
(2) adding an ionic surfactant to the reactor; or
(3) adding a mixture comprising an antioxidant to the product under conditions sufficient to avoid formation of significant amounts of insoluble metal or metal compounds derived from said metal alkyl compound; or
(4) purging said post-reactor heat exchanger with an inert gas under conditions to remove metal oxide from the post-reactor heat exchanger.
In another embodiment, the invention relates to novel compositions comprising an ethylene/α-olefin multiblock interpolymer and a metal ester. The ethylene/α-olefin multiblock interpolymers may be characterized before any crosslinking by one or more of the following characteristics:
(1) an average block index greater than zero and up to about 1.0 and a molecular weight distribution, Mw/Mn, greater than about 1.3; or
(2) at least one molecular fraction which elutes between 40° C. and 130° C. when fractionated using TREF, characterized in that the fraction has a block index of at least 0.5 and up to about 1; or
(3) an Mw/Mn from about 1.7 to about 3.5, at least one melting point, Tm, in degrees Celsius, and a density, d, in grams/cubic centimeter, wherein the numerical values of Tm and d correspond to the relationship:Tm>−6553.3+13735(d)−7051.7(d)2; or
(4) an Mw/Mn from about 1.7 to about 3.5, and a heat of fusion, ΔH in J/g, and a delta quantity, ΔT, in degrees Celsius defined as the temperature difference between the tallest DSC peak and the tallest CRYSTAF peak, wherein the numerical values of ΔT and ΔH have the following relationships:ΔT>−0.1299(ΔH)+62.81 for ΔH greater than zero and up to 130 J/g,ΔT≧48° C. for ΔH greater than 130 J/g,
wherein the CRYSTAF peak is determined using at least 5 percent of the cumulative polymer, and if less than 5 percent of the polymer has an identifiable CRYSTAF peak, then the CRYSTAF temperature is 30° C.; or
(5) an elastic recovery, Re, in percent at 300 percent strain and 1 cycle measured with a compression-molded film of the ethylene/α-olefin interpolymer, and has a density, d, in grams/cubic centimeter, wherein the numerical values of Re and d satisfy the following relationship when ethylene/α-olefin interpolymer is substantially free of a cross-linked phase:Re>1481−1629(d); or
(6) a molecular fraction which elutes between 40° C. and 130° C. when fractionated using TREF, characterized in that the fraction has a molar comonomer content of at least 5 percent higher than that of a comparable random ethylene interpolymer fraction eluting between the same temperatures, wherein said comparable random ethylene interpolymer has the same comonomer(s) and has a melt index, density, and molar comonomer content (based on the whole polymer) within 10 percent of that of the ethylene/α-olefin interpolymer; or
(7) a storage modulus at 25° C., G′(25° C.), and a storage modulus at 100° C., G′(100° C.), wherein the ratio of G′(25° C.) to G′(100° C.) is in the range of about 1:1 to about 9:1.
The ethylene/α-olefin multiblock interpolymer characteristics (1) through (7) above are given with respect to the ethylene/α-olefin interpolymer before any significant crosslinking, i.e., before crosslinking. The ethylene/α-olefin interpolymers useful in the present invention may or may not be crosslinked depending upon the desired properties. By using characteristics (1) through (7) as measured before crosslinking is not meant to suggest that the interpolymer is required or not required to be crosslinked—only that the characteristic is measured with respect to the interpolymer without significant crosslinking. Crosslinking may or may not change each of these properties depending upon the specific polymer and degree of crosslinking.